Refractory anemia with ringed sideroblasts (RARS) is an extremely rare type of myelodysplastic syndrome in children. We describe a 10-year-old boy with RARS presented with pancytopenia. He remained relatively stable with only a few transfusions until age of 20 years, when he underwent an allogeneic bone marrow transplantation (BMT) because of increased transfusion requirements. He remains in complete chimeric state at 20 months posttransplant with normal hematologic parameters. To our knowledge, this is the first description of successful BMT in a patient with childhood-onset RARS. The indication of BMT for this rare disorder in children is discussed.
Anemia, Refractory/therapy* ; Anemia, Sideroblastic/therapy* ; Bone Marrow Transplantation* ; Case Report ; Child ; Human ; Male ; Transplantation, Homologous

Anemia, Sideroblastic ; congenital ; diagnosis ; therapy ; Child ; Erythrocyte Transfusion ; Female ; Humans ; Hyperbilirubinemia ; etiology

It was thought that delta-aminolevulinate synthase (ALAS) is the rate-limiting enzyme in the heme biosynthetic pathway. Actually there are two isozymes of ALAS and ALAS2 (erythroid delta-aminolevulinate synthase), they play the leading role in the hemoglobin biosynthetic pathway. Mutations in ALAS2 gene causes X-linked sideroblastic anemia (XLSA). About 25 different mutations in ALAS2 gene have been identified in XLSA patients and two of them were reported by our laboratory. It is possible to cure the patients with XLSA by gene therapy because it is a single gene disorder.
5-Aminolevulinate Synthetase ; genetics ; Anemia, Sideroblastic ; genetics ; therapy ; Chromosomes, Human, X ; genetics ; Genetic Linkage ; Genetic Therapy ; methods ; Humans ; Mutation

X-linked sideroblastic anemia (XLSA) is caused by mutations of erythroid-specific 5-aminolevulinate synthetase (ALAS2) gene. In this study a eukaryotic expression vector of ALAS2 was constructed and transfected into eukaryotic cells to observe the expression of ALAS2 gene. The full length cDNA of ALAS2 gene was inserted into plasmid pDs-red2-N1, named pDs-red2-N1/ALAS2. Then, the vector was transfected into K562 cells via electroporation. At 48 hours after transfection, total RNA from K562 cells was extracted, expressions of ALAS2 gene and protein with red fluorescence in the K562 cells were detected by RT-PCR and flow cytometry, respectively. The vector was also transfected into COS 7 cells via liposome. Both mRNA and protein expression in COS7 cells were detected by RT-PCR and fluorescence microscopy. The result showed that after the pDs-red2-N1/ALAS2 eukaryotic expression vector was digested by KpnI and BamHI, two fragments of 4 700 bp and 1 764 bp were displayed by electrophoresis on agarose gel. Sequence method confirmed that the sequence was correct. RT-PCR amplified the total RNA extracted from the transfected K562 and COS7 cells, and could find mRNA of ALAS2 gene that can't be found in K562 and COS7 cells usually. The expressions of both fluorescein and ALAS2 were significantly increased. The percentage of positive cells reached about 19.2% and 10.7%, respectively. ALAS2 expression lasted for 10 days in COS7 cells and the peak was at the third day. It is concluded that the eukaryotic expression vector of ALAS2 gene is successfully constructed; K562 and COS7 cells transfected with the vector via electroporation and liposome can express ALAS2 protein. So, the vector has the potential in gene replacement and can be used for patients with XLSA in future.
5-Aminolevulinate Synthetase ; genetics ; Anemia, Sideroblastic ; genetics ; therapy ; Animals ; COS Cells ; Chromosomes, Human, X ; Genetic Linkage ; Genetic Therapy ; Genetic Vectors ; Humans ; K562 Cells ; Microscopy, Fluorescence ; Reverse Transcriptase Polymerase Chain Reaction